Dynamo-electric machine



June 23, 1925.

H. M. HOBART DYNAMO ELECTRIC MACHINE Filed March 25, 1924 Inventor: H envy M. H obarb, b M4 if His Attorney.

Patented June 23, 1925.

UNITED STATES PATENT osrlcs.

mY'I- HOBART, OI mus mu, I" YOBI, ABIGI'OI. 1'0 Gm MO (20124, A CORPORATION 01' m You DYIAIO-ILMBIO ncmn.

Application lied larch 85, 10M. lerlal lo. 701)".

- To all whom it may concern:

Be it known that I, Hmsnr M. Hpaan'r, a citizen of the United States, residing at Niskayuna in the county of Schenectady,

State of New York, have invented certain new and useful Improvements in Dynamo- Electric Machines, of which the following is a s ification.

invention relates to dynamo electric 1 mac ines and particularly to such machines which are provlded with means for enclosin the stator windings in an insulating an cooling medium, such as oil, in contact therewit The beneficial results obtained by immersing electrical windings in an oil, such as is commonly used for this purpose, are well known. Its use, however, in the past has been limited principally to stationa a aa0 ratus, such as transformers and t e e. Apparatus of this character, having no ing parts is well adapted to the use of o1l m this manner, since all parts of the device can be totally immersed. In the case of roill tary ap aratus, however, it is usuall impractical to immerse the winding of t e rotary parts owing to the relatively high viscosity of oil as compared with air, which would retard the moving parts and increase 80 the running li ht losses within the machine and therefore ecrease its eflicienc In large dynamo electric mac ines and particularly in alternating current motors and generators it is usual to locate the high voltage windings on the stationary portion of the machine. In such machines it is possible to im rove the insulation and cooling of such mac ines to such an extent that the use of means which will 't the stator windingstobeimmersedmamediumsuchasa or oil is warranted. The rotor under conditions is permitted to rotate in air as is standard practlce.

In order to accomplish this it is necessary 45 to provide a separating partition between the stator and rotor whic will maintain the oil about the stator win and at the same time not interfere with e magnetic circuit the stator and rotor windings. .Such

9 a partition to be eficient must be non-metaL lie or be one which has considerable resistance to eddy currents. In accordance with my invention, I provide a partition which p0 all the above desirable features, which is simple and is easily constructed.

For a better understanding of myinvention, reference may be had to the following description taken in connection with the accompanying drawin in which Fig. 1 is a sections elevation o a dynamo electric mu chine embodying m invention, and F 2 and 3 show mod cations of a partition built in accordance with my invention.

Referring to Fig]. 1, a dynamo electric machine is shown avlng a stator provided with a winding 11 which is ada ted to be immersed in an insula and medium, such as oil. Moun and adapted to rotate within the stator 10 is a rotor 12 and interposed between the stator 10 and rotor 12 in the air p is a partition 13 of non-magnetlc material and high electrical resistance which mechanically separates the two. In the particular am out shown the artition 13 is composed o a cylinder of a p enol condensatiomproduct or the like. It may be made of shellaced paper or a paper lmpregnated with a phenol condensation product. The stator 10 is mounted in a tame 21 which is provided with end frames 22. The end frames 22 are provided with flanges 14 which cooperate with similar flanges 15 on end members 23 to secure said end members in position and provide a support for the rotor bearings. The partition 13 is sup rted between the stator 10 and rotor 12 y being inter d between the flanges 14 on the end mes 22 and the flanges 15 on the end members 23: After the artition 13 has been laced in position, the anges 14 and 15 are olted or otherwise secured together to thus provide an oil tight partition between' the stator 10 and the rotor 12. As a result of the above construction, I provide an effective artition between the stator and the rotor w 'ch will maintain the liquid or other medium in contact with the stator windings 11 without interfering with the successful operation of the and also provide an arrangement of theparts which can be assembled and dibled with a minimum of inconvemence. The enclosing casing can be of any convenient shape and S126 depending upon the results desired, for instance, if used to contain an insulating medium it can be made relatively small an where cooling is of rimary importance it can be made relative large to provide for a large amount of coo ing med1um and radiatin surface. The cooling capacity of the liquid or other medium within the cas ng can also be increased by additional cooling means. In the drawing I have shown coils of pi e 16, which when connected to a water supp y permit water to circulate therethrough and carry ofi a considerable portion of the heat from the cooling medium.

In addition to improved msulatlon and cooling of the machine, the oil, when oil is employed, also protects the windings from moisture when used in dam places such as in h dro-electric stations. I t also keeps the win ings free from dirt. Anothenbenefit which results from immersing the wmdm 11 in oil is that the end turns can be ma e much shorter than is permissible in air. When these end turns are exposed to air they have to be made large to provide cree age surface to thus prevent puncture of t e windings at these points due to corona. When immersed in oil the deteriorating effect of corona on the insulation is substantially eliminated and as a result the life of the insulation is materially lengthened and its properties improved. This is also the case when the windings are immersed in a gas such as hydrogen. A saving in the cost of the insulation might also be effected by wrapping the windings with a porous ta e of cotton or other like material and permitting the oil or gas to permeate the tape and come into contact with the conductors, the tape serving primarily to separate the conductors from each other and the slots, in much the same manner as is commonly practiced in transformer construction. As an alternative, spacers may be provided in the conductor slots to provide channels between the windings and the sides of the slots in which case the insulating medium may circulate freely therethrough.

In Fi 2, the partition 13 is shown composed 0 three separate pieces, a middle section 17, which is composed of non-ma etic material and end sections 18 of a suitable metal which can be welded or otherwise secured to the frame of the machine. In this embodiment the end pieces are provided with circumferential groves 19 into which the middle section 17 is clamped or otherwise secured to provide an oil tight joint between the sections.

Fig. 3 is a modification of the partition shown in Fig. 1. The middle section is perforated and made thinner by providing annular 20 on each side of the partition 13' and the insulating material 15' is laced in these annular a The perorations in the middle section are so aha and arranged that a relatively high resistance to circulating and eddy currents is established and thus heating of the artition 13 at this point is material 5' reduc These perforations mabe fille with any suitable filling suc as shellaced pulp or a phenol condensation roduct before the covering 15 is applied and thus a smooth surface can be secured at the middle section. This construction provides a artition which is smooth on each side an of sufficient strength to withstand the pressure caused by the insulatin or coolin medium. From the above it wi 1 be seen t at I have provided a means for maintaining an insulating and cooling medium in contact with the stator windings of a rotary type of dynamo electric machine, which will not interfere electrically with the successful operation of the machine and generally improve the machine by reducing corona about the windings, improving the insulation and increasing the coolin so that the machine ma be operated at igher current density an higher voltages.

While I have shown and described the dynamo electric machine havin an annular enclosing casing which is com etely closed, I desire to have it underst that the casing can be constructed with the top open, and a cover provided in the same manner as is customary with other immersed electrical ap aratus. The casing may also be provi ed with an auxiliary storage tank or conservator to take care of the expansion and contraction of the oil due to chan es in temperature and also prevent sludging of the oil.

Although I have described m invention with considerable detail and wit respect to certain articular forms of construction, I do not esire to be limited to such details since many changes and modifications ma well be made without departing from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. In a dynamo electric machine, the combination o a frame, a stator winding, a rotor, and a metal partition comprisin a perforated middle section having insulatlng material disposed on each side sealing said perforations and non-perforated end sections, said middle section lying in the air gap between said stator winding and said rotor, said end sections coo rating with said middle section and said me to form a casing around said stator winding for containing an insulating medium.

2. In a dynamo electric machine, the combination 0 thereof for .a frame, a stator winding, a

Ill

rotor, and a partition extending axially bematerial in said depressions and holes, said tween said stator and rotor and cooperatreduced section being located within the air ing with said frame to form a casing about gap between said stator winding and said 10 said stator winding, said partition having a r orreduced middle section formed 1) a de res- In witness whereof, I have hereunto set sion on its inner and outer sur aces, oles my hand this 24th da of March 1924. connecting said depressions and insulating HE RY M. HCSBART. 

